2015. november 11., szerda

Popiela et al. (2015) Acta Botanica Gallica

Elatine trianda Schkuhr is the most widespread species within the genus Elatine L.; it can be found in all continents, except Antarctica, but the majority of the locations have been recorded in Europe. The study is based on an extensive dataset of literature, herbaria and web data, which spans the period 1828–2012. The range of the species in Europe is disjunctive; it covers the southern and western parts of the Central European Plain and the northern shores of the Baltic Sea, it can also be found along some river valleys. In Central Europe many localities especially isolated ones in northern part of the range are historical now. According to the dataset we determined that E. triandra can be observed between May and October. We also found a remarkable historical decrease of observation time. We found that species observation has a near significant shift since 1828 that correlates to changes in environmental variables. Depending on the environmental conditions individuals of the taxon could develop in two forms: terrestrial and aquatic. The aquatic form is characterized by twice longer stems and internodes, and also almost twice longer lamina and petiola. E. triandra seeds show consistent characteristics both in terms of forms and populations. Our studies show that the best diagnostic feature, in addition to the construction of flowers, are size, shape and surface structure of seeds. In Central Europe E. triandra occurs exlusively in communities classified to the Isoëto-Nano-Juncetea, however the number of species characteristic for the class and lower syntax in patches decreases from north to south of the continent.

chorology, ephemerophyte, Isoëto-Nano-Juncetea, phytogeography, vegetation, morphology, maps, phenology

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